Vacuum treating process



April 1952 A. H. HEINEMAN VACUUM TREATING PROCESS Filed NOV. 14, 1947 five/W71 /6 @22 Patented Apr. 22,1952

VAGUUM TREATING PROCESS Arnold H. Heineman, Chicago, 111., assignor to Guardite Corporation, Wilmington, Del., a corporation of D'eiaware Application November 14, 1947, Serial No. 786,042

6 Ciaims.

This invention relates to a .vacuum treating process and is an improvement upon the processes described in Merriam and Wiles Patent No. 2,080,179 filed May 11, 1937, and Bailey Patent No. 2,217,933 filed May 2, 1938.

The Merriam and Wiles patent describes a process for treating bulk materials in which the materials are made pervious tossteam or other gas by replacing the atmosphere or air normally around the bulk material with an atmosphere of steam generated by steam boiled from moisture in the materials by reason of lowered air pressure. The Bailey patent describes a process for moistening products under vacuum and in an atmosphere of steam such as is produced by the Merriam and Wiles process, by injecting superheated water into the vacuum under a high self-generated pressure whereby extremely fine particles of liquid, designated as a micromist are produced which will penetrate the bulk material when such material is free from air or other non-condensible gas.

The Merriam and Wiles process further contemplates the steaming of bulk materials once they have been freed from air. The purpose of the steaming is normally to increase the moisture content. Inasmuch as condensation of steam upon the bulk product increases its temperature by a definite number of degrees for each per cent of condensed steam, the amount of moisture which can be so added is limited. For that reason the Bailey process of introducing water in extremely fine droplets permits the addition of more water within a given temperature range. For the same reason desuperheating of the steam is advi'sable to permit the addition of more water within a given temperature range, and is normally employed.

It has hitherto been the practice to introduce the fine particles of water in such a manner that after their introduction to the vacuum zone they impinge upon a baffle arranged more or less remote from the injection nozzle. This not only produced local spattering which had-to be protected against, but the impingement tended to increase the particle size and destroy some of the value of the process. Desuperheating was normally accomplished with relatively cold water through which the steam was passed. The handling of this water likewise created a problem.

, The present invention provides means for overcoming both sets of difiiculties. In the preferred form this is" accomplished b directing the stream of superheated water and the current of superheated steam into each other, preferably in headon collision. In this way the velocity of the 2 stream of fine particles of water is cut down so that no impingement on a solid surface as a stream occurs, and on the other hand the steam is effectively desuperheated in spite of the superheated temperature of the initial water stream.

If desired, however, a pair of spray nozzles may be directed at each other, or a ring of alternating micromist' and steam nozzles directed toward a common center.

The invention is illustrated diagrammatically in the drawings in which,

' Fig. 1 is a diagrammatic transverse sectional elevation through the upper portion of a vacuum treating chamber;

Fig. 2 is a crosssection of a micromist pipe;

Fig. 3 is a similar cross-section of asteam pipe;

Fig. 4 is a broken sectional plan view of the pipe shown in Fig. 2; and

Fig. 5 is a corresponding view of the pipe shown in Fig. 3.

As illustrated in the drawings, l0 represents a vacuum chamber supplied with the usual means for producing a substantially perfect vacuum; I l represents a hogshead of tobacco within the chamber; 12 represents a false ceiling therein; l3

represents a pipe connected to a source of superheated water; and H represents pipes connected to a source of steam under superatmospheric pressure.

As shown in Figs. 2 and 4, the pipes l 3 are probers I5 which are welded to the pipe and communicate therewith by means of a relatively large opening 16. The apex of each nozzle is drilled and supplied with a threaded plug H which is likewise drilled with an opening 18. The plugs I! are removable so that the size of the opening l8 may be varied as desired. It will be noted that the openings are directed in a substantially horizontal line toward the corresponding openings 20 in the steam lines l4. These openings 20 are likewise drilled in plugs 19 removably held in the pipes [4.

The size of the openings vary according to the distance, the temperature and pressure of the steam and the temperature and pressure of the water. For an operation in which the openings are about 5 feet from each other, a steam pressure of about 22 pounds absolute, a pressure on the water about pounds absolute (with its temperature corresponding thereto), an opening of inch in the water line, and an opening of A to V inch in the steam line are satisfactory. This is in connection with a vacuum, the pressure of which initially may be in the neighborhood of 1 to inches of mercury absolute and will increase until the pressure is about 8 to 10 inches absolute.

The openings have been placed as little as 2 feet apart with satisfactory operation. The steam pressure may of course be greatly increasedor considerably diminished. It is usually worthwhile to employ whatever waste steam is available in the plant, and this ordinarily varies from 2 pounds gauge upward. The pressure on the water should be as high as can be practically obtained in order to produce particles of the smallest size, where the water stream is employed for impregnating purposes.

While I have shown and described my invention in its preferred embodiment, it isto" be understood that it is capable of manymodifications. Changes, therefore, in the construction and arrangement may be made without departing from the spirit and scopeof the invention asdisclosed in the appended claims.

I claim:

1. The method of desuperheating steam which comprises introducing substantially saturated steam into a high vacuum, and into head-on collision with a stream of fine particles of water and steam formed by injection of highly superheated water to the vacuum. I

2. The process which comprises introducing a stream of superheated waterunder superatmospheric pressure into a chamber containing a material to be moistened and containing an atmosphere substantially of steam under low subatmospheric pressure. whereby the stream of water explodes and produces steam and very fine particles of water, and substantially arresting the velocity of the stream by means of another fluid stream flowing head-on into the stream of water.

3. The method of claim 2 in which the axes of the two streams of fluid and superheated water are substantially in alignment and flow in opposite directions.

4. The method of claim 2 in which the points of introduction of the two streams are approximately 2&5-5 feet apart.

5. The method of claim 2 in which the headon collision occurs before the stream of superheated water impinges on any solid surface.

6. The method of claim 2 in which the head-on collision occurs before the stream of superheated water impinges on any solid surface and in which the axes of the two streams of fluid and superheated water are substantially in alignment and flow in opposite directions.

ARNOLD H. HEINEMAN;

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

1. THE METHOD OF DESUPERHEATING STREAM WHICH COMPRISES INTRODUCING SUBSTANTIALLY SATURATED STREAM INTO A HIGH VACUUM, AND INTO HEAD-ON COLLISION WITH A STREAM OF FINE PARTICLES OF WATER 